Digital versatile discs (DVDs) are information storage devices used for storing data such as audio, video, and computer software. The storage and playback mechanism used in DVDs closely resembles the mechanism used in compact discs (CDs) and DVD players use the same laser technology as CD players. Briefly, both DVDs and CDs store information as a pattern of pits formed in a metallic substrate. The pit patterns form digital words and can be read by shining a laser beam on the disc surface and detecting the reflected beam. However, the information storage capacity of a typical DVD is much higher than a CD. Presently available DVDs have a variety of capacities which depend on the technology used to manufacture the discs. Single-layer technologies can be either single or double-sided with capacities of 4.7 gigabytes and 9.4 gigabytes, respectively. Dual layer technologies will soon be available which use single or double sided capacities that hold approximately 8.5 gigabytes per side. This high information storage capacity makes DVDs suitable for storing not only audio information, but also video information and large amounts of computer data as well.
DVD players have many CD player features, such as the ability to play selections in any order desired and the ability to read information from any point on the disc. DVDs, however, can store information in several formats. For example, DVDs which are used to store video information, hereinafter called DVD-VIDEO discs, may use various known information compression algorithms, such as MPEG-2 for video compression/decompression. A DVD may also include high fidelity sound data, for example, in uncompressed linear pulse code modulated data streams which have sample rates between 48-90 kHertz and are sampled at 16 or 24 bits. Still other DVD versions, hereinafter called DVD-ROM discs, can store digital data for computer use, and the data may also be compressed on these discs.
Conventionally, a DVD player accepts a user's input through an input device such as a dedicated infrared (IR) remote control device. The remote control device typically responds to a user's activation of a button by translating button information, e.g. row and column information, into a series of infrared light pulses. The light pulses are keyed on and off at a base rate of 30 to 40 KHz in order to distinguish the control signal from ambient light. The train of light pulses are generally formatted to include a header, which identifies a target device, and command information. The DVD player receives the light pulses and converts them into a binary electronic representation corresponding to the button that had been depressed by the user. For example, assume that a DVD player's dedicated remote control device includes a rectangular array of buttons, with the button in the upper left corner of the array being an "on/off" button. Assume further that the remote control device emits a series of light pulses corresponding to a binary value of "00" in response to the depression of this button. When it receives the "00" series of light pulses from the remote control device, the DVD player, which continuously supplies power to a "monitoring circuit" even when the player is "off", recognizes, through means of an application program included within the DVD player, that the "00" sent by the remote control devices is a "power" command and the DVD player responds accordingly.
Although a dedicated remote control system such as just described may work reasonably well, there are a number of input devices which a user may prefer for any of a variety of reasons. Another IR remote control device may, for example, be more aesthetically appealing, or it may provide a more comfortable layout, or it may provide additional features, such as an anti-loss feature, which makes it more appealing to a user. Other input systems, such as a speech input system, a trackball, or mouse, may also be preferred by a particular user. Unfortunately, a typical dedicated remote control DVD player system cannot accommodate a variety of input devices. Even another IR remote control device with the same basic physical button layout may not be compatible, because the button definitions may vary. For example, the button in the upper left corner may be defined as a "reverse" button, rather than a power button and the DVD player's application program would misinterpret the transmitted button information. Alternatively, the same button location may have the same definition, but the pulse code produced may be different, so that, for example, a "power" button in the upper left corner of one remote control device produces a "00" output and the "power" button in the upper left comer of another remote control device produces a "01". Although it is conceivable that the DVD player's application program could be re-written to accommodate additional input devices, this would require a substantial effort each time a new input device is added to the DVD player's repertoire.
With all the variety of button arrangements and definitions, the variety of input mechanisms, such as speech, infrared, etc, and the continuous development of new input devices, accommodating a variety of input devices and accommodating new input devices as they are developed becomes a substantial challenge. Given the availability of a wide variety of input devices and the continuous development of new input devices, it would be highly desirable to provide a DVD player system which accommodates a variety of input devices and is capable of accommodating new input devices without requiring that its entire application program be rewritten. Additionally, it would be highly desirable for a DVD player to provide arbitration among multiple input devices to thereby reduce confusion associated with the simultaneous activation of more than one input device.